Something odd.....failure to raise a ground bur on one of my scrapers.

[Odie]

I was turning last night, and something odd happened with one of my scrapers. This scraper is M2 HSS, and has been in use for quite some time with no problems raising a ground bur. This particular scraper failed to raise a ground bur as it usually did. My grinding wheel is Norton 8" SG 80gt. When I raise a ground bur, I usually run my finger to test it, and there was none detectable this time. This scraper performed poorly with this non existent bur. I tried raising a manually raised bur on this scraper, and no problems there....the manually raised bur appears and functions as normal......but, there is no detectable bur coming off the grinding wheel.

I tested using a few other scrapers, and the ground bur is the same as usual.....easily detectable with the finger on these other scrapers.

I used a diamond dresser and tested again......no change.

The platform angle was unchanged.

Anyone have any idea what the problem with this one scraper might be?

Anyone ever experience this?

Have I reached a spot where the M2 specs might be different? (Several inches of this scraper have been used up, and it previously produced a ground bur successfully.....but, not this time.)

-----odie-----

 

[Gary Beasley]

It may have been edge hardened or even have a softer metal bonded to the harder stuff. I see this on the guillotine blades of the cutting machines in print shops. Once sharpened past the harder steel into the backbone steel it will not hold an edge and needs to be retired. I guess you need to mark that one for hand raised burrs only.

 

[robo hippy]

What Gary said would be my first guess. I do relieve the bottom part of the bevel on all of my tools, scrapers included. I would also suggest that you take a magic marker and blacken the bevel, then sharpen again and make positive that the platform/angle has not changed. I would think that even if you did get to the 'softer' metal in the scraper, it would still leave a burr....

robo hippy

 

[Odie]

What Gary said would be my first guess. I do relieve the bottom part of the bevel on all of my tools, scrapers included. I would also suggest that you take a magic marker and blacken the bevel, then sharpen again and make positive that the platform/angle has not changed. I would think that even if you did get to the 'softer' metal in the scraper, it would still leave a burr....

robo hippy

I was thinking the same thing, robo......even if the metal hardness or composition had changed, it still should leave a bur.

In this case, the platform hasn't changed angle.....since I sharpened several other scrapers without any adjustments, and those other scrapers left a good ground bur. All of my scrapers have the same bevel angle, the only thing that changes is the height and width of the steel, and how the presentation differs......the platform angle never changes for either ground, or manually raised burs.

I guess you need to mark that one for hand raised burrs only.

^^^^^That's exactly what I did, Gary.....thanks.



Still, it's a puzzle that seems yet to be solved......

-----odie-----

 

[Randy Heinemann]

It's unclear from your post, but I assume you tried burnishing it to create the burr, by running the burnisher along the edge? I know that you might not do this every time you sharpen your scrapers, but I have found that many times this type of burr is superior to that created just by sharpening on a wheel. Since you have much more experience than I do, I would imagine whatever method you have used in the past should work. You might try grinding more off to get to a truly "fresh" edge. Just some suggestions from my more limited experience with turning scrapers. I know more about scrapers used in other types of woodworking.

 

[Odie]

It's unclear from your post, but I assume you tried burnishing it to create the burr, by running the burnisher along the edge? I know that you might not do this every time you sharpen your scrapers, but I have found that many times this type of burr is superior to that created just by sharpening on a wheel. Since you have much more experience than I do, I would imagine whatever method you have used in the past should work. You might try grinding more off to get to a truly "fresh" edge. Just some suggestions from my more limited experience with turning scrapers. I know more about scrapers used in other types of woodworking.

Yes, Randy..... What I've called the "manually raised bur" is the same thing as a burnished bur.....I use a Veritas jig for this, which utilizes a carbide pin for raising the bur.

I agree....the burnished, or manually raised bur is superior to the ground bur, and their applications in woodturning are quite different.

-----odie-----

 

[Neil S]

I would think that even if you did get to the 'softer' metal in the scraper, it would still leave a burr....

It just wouldn't last very long, if at all.

 

[Michael Brown]

Is it possible that the heat treat needs to be repeated?

 

[Odie]

It just wouldn't last very long, if at all.

Just coming in from the shop now.....just past midnight!

I did a back-to-back comparison of the questionable scraper and another of the same configuration,.....on the same area of the same bowl. It did seem to perform inadequately, when compared to the other, in that test.

I decided to retire the bad scraper, and grab a brand new scraper to replace it.

Pretty much concluded there is something wrong with the steel in the scraper in question.....no proof, but sometimes it's better to reject it, rather than mess with it.

-----odie-----

 

[Bill Boehme]

Some M2 turning tools are induction hardened and tempered (an electromagnetic heating process that tempers the business end of the turning tool). The tempering extends only about two inches from the tip on some low-end turning tools. High-end turning tools usually have the entire usable working length of the tool tempered.

 

[Odie]

Some M2 turning tools are induction hardened and tempered (an electromagnetic heating process that tempers the business end of the turning tool). The tempering extends only about two inches from the tip on some low-end turning tools. High-end turning tools usually have the entire usable working length of the tool tempered.

That could very well be it, Bill.....thanks.

-----odie-----

 

[Dean Center]

One other possibility is that your platform, or possibly how you applied the bevel to the wheel, the prior time you ground it was off. Then the next time you went to grind a burr, the bevel angle was slightly blunter, and you didn't actually grind the top edge. That's less likely for you than for most of us, Odie, because you're very precise, but my platform will 'rock' slightly depending on how I press down on the tool shaft. Do you recall the sparks going over the top of the scraper when you tried to put the burr on?

 

[Neil S]

Some M2 turning tools are induction hardened and tempered (an electromagnetic heating process that tempers the business end of the turning tool). The tempering extends only about two inches from the tip on some low-end turning tools. High-end turning tools usually have the entire usable working length of the tool tempered.

In the past I've also had the opposite happen. The first 3/8" of the tip of the tool is over tempered (too soft) and it is not until that is ground away that a better tempered hardness is exposed. Not seen that recently with modern more controlled heat treatment processes, but worth noting.

I don't throw a 'new-old' tool into the bottom drawer until I've ground a bit more off the end in case there is some good steel hidden away in there!

 

[Odie]

One other possibility is that your platform, or possibly how you applied the bevel to the wheel, the prior time you ground it was off. Then the next time you went to grind a burr, the bevel angle was slightly blunter, and you didn't actually grind the top edge. That's less likely for you than for most of us, Odie, because you're very precise, but my platform will 'rock' slightly depending on how I press down on the tool shaft. Do you recall the sparks going over the top of the scraper when you tried to put the burr on?

Howdy Dean.....I can't say specifically that I saw sparks coming over the top, but I often do. I've resharpened scrapers so many times, that noticing the sparks may be at the subconscious level anymore! I always check for the bur with my fingers every time, and I reground this particular scraper several times in the process of experimenting with it.

My platform is the Oneway Wolverine, and it's pretty darn rigid....so I don't think that could be the problem.

At this point, I've already removed the scraper from it's handle and stored it away.....I feel pretty confident that Bill was right, and there is a problem with the steel.

-----odie-----

 

[Gary Beasley]

Now that its out of the handle may as well get out a torch and see if it will take a heat treat again.

 

[Lars Hansen]

Odie, have you tried to run a metal file over the edge of the scraper in question and compare it to another (functional) scraper? Bill's explanation sound very likely, and if you're down to a less hardened or even non hardened part, the file wil bite into the steel instead of skating as it should on a turning tool.

 

[Odie]

Odie, have you tried to run a metal file over the edge of the scraper in question and compare it to another (functional) scraper? Bill's explanation sound very likely, and if you're down to a less hardened or even non hardened part, the file wil bite into the steel instead of skating as it should on a turning tool.

I wish I had thought of that before......thanks, Lars.

-----odie-----

 

[Doug Freeman]

I have had the same happen, due to not grinding to the edge. I have an LV burnisher as well. It can turn an aggressive burr, depending on pressure applied. It can take some extra matl removal to get past the burnished area, and it can be very difficult to see it. Then again, I know you’ve been at this a while and have sharpened scrapers once or twice, Odie, so ???

Going through the hardened area is a likely suspect, and the file check is a good idea. If you figure it out please report back.

 

[Russ Braun]

Now there’s a great argument for getting a new tool!! Well thought out Odie!!

 

[Dean Center]

Also an argument for not trying to get the last mm of length out of a tool. My favorite sport.

 

[Odie]

Odie, have you tried to run a metal file over the edge of the scraper in question and compare it to another (functional) scraper? Bill's explanation sound very likely, and if you're down to a less hardened or even non hardened part, the file wil bite into the steel instead of skating as it should on a turning tool.

Going through the hardened area is a likely suspect, and the file check is a good idea. If you figure it out please report back.

Last evening, I did the file test on the suspect scraper.....and, indeed it didn't skip, but cut into the metal.

Well, I guess that's that.....and conclusive evidence that the hardening has reached a spot where it no longer was up to standard.

-----odie-----

 

[Dean Center]

Odie, you're pretty capable mechanically. I bet you could re-harden and temper it. John Lucas could give you a recipe, Alan Lacer has a DVD about the process, surely somebody out there where all the trees grow is a blacksmith or farrier and could walk you through it (or do it for you). You've got the scraper out of the handle....

Edit: There's one in Frenchtown--oriented to architectural metal work, but maybe they also understand the process. https://missoulablacksmith.com/

 

[Odie]

Odie, you're pretty capable mechanically. I bet you could re-harden and temper it. John Lucas could give you a recipe, Alan Lacer has a DVD about the process, surely somebody out there where all the trees grow is a blacksmith or farrier and could walk you through it (or do it for you). You've got the scraper out of the handle....

Edit: There's one in Frenchtown--oriented to architectural metal work, but maybe they also understand the process. https://missoulablacksmith.com/

Hi Dean....

The scraper in question is one of my homemade scrapers fashioned from a metal lathe cutter bit in my homemade pvc handle. The dimensions of this cutter as I receive it, is 1/2" x 1/2" x 6". The scraper is mostly used up anyway. I can only use about 1/2, or about 3" of the total length of the cutter bit.

Your suggestion is probably best suited for someone who needs to save a more expensive full length commercial scraper. This one is just not worth saving IMNSHO!

-----odie-----

 

[Doug Freeman]

@odie did you check the other end of the blank, that was stuck in the handle? May well be fine to use. I’m guessing you just randomly chose an end to grind.

 

[Odie]

@odie did you check the other end of the blank, that was stuck in the handle? May well be fine to use. I’m guessing you just randomly chose an end to grind.

Hi Doug......

The metal cutting bits are squared on the ends, and need to be shaped by the end user for use. In order to do that, it takes quite a bit of forming the initial round nose that I use. I probably could get a little more use out of this one bit by doing that, but the amount of effort to prepare it for use, considering how much available length there is left, pretty much points to a conclusion that it's just not worth the effort.

-----odie-----

1/2" x 6" OAL Ground Square Tool Bit HSS - RDX

Over 60 years in the business, with warehouses located in Warren, Michigan and Tulsa, Oklahoma. Place your order now via phone, fax, or the web at www.wttool.

www.wttool.com

 

[Doug Freeman]

Understood - I’m more curious whether the other end is hard, and just the center is soft. I would say you got your $’s worth out of it!

I use 3/16” square bits, 4” long, cut to 2” for hollowing bits. I have not found them to be soft in the middle, maybe I was lucky. I may get some larger hss pieces for scrapers etc.

 

[Bill Boehme]

Odie, you're pretty capable mechanically. I bet you could re-harden and temper it. John Lucas could give you a recipe, Alan Lacer has a DVD about the process, surely somebody out there where all the trees grow is a blacksmith or farrier and could walk you through it (or do it for you). You've got the scraper out of the handle....

Edit: There's one in Frenchtown--oriented to architectural metal work, but maybe they also understand the process. https://missoulablacksmith.com/

The type of tool steels that Alan Lacer and others anneal, harden, and temper for toolmaking (hook tools, etc) are high carbon tool steel such as O-1 and W-1. It is well beyond the capability of even Alan Lacer to heat high-speed tool steel to the temperatures required for annealing, hardening, and tempering. M2 high-speed tool steel for example is quenched at 2200° F and tempered at 1150° F for 62 Rockwell C hardness. The times and temperatures are fairly critical to get reliable results. It appears that the Missoula Blacksmith is mainly working with mild steel and iron. Odie should talk to him, if for no other reason than new shoes for Betsy.

 

[Don Wattenhofer]

The type of tool steels that Alan Lacer and others anneal, harden, and temper for toolmaking (hook tools, etc) are high carbon tool steel such as O-1 and W-1. It is well beyond the capability of even Alan Lacer to heat high-speed tool steel to the temperatures required for annealing, hardening, and tempering. M2 high-speed tool steel for example is quenched at 2200° F and tempered at 1150° F for 62 Rockwell C hardness. The times and temperatures are fairly critical to get reliable results. It appears that the Missoula Blacksmith is mainly working with mild steel and iron. Odie should talk to him, if for no other reason than new shoes for Betsy.

Thanks for clarifying the differences between the aloys, this whole conversation was getting out of control.

 

[Dean Center]

Yes, thanks, Bill. My oven gets hotter than I've ever needed to use, but probably not 2200.

Odie, learning that you are using those short steel blanks for your scrapers led to an "Aha!" moment. Those must be what you use to get the round groove on your bowl bottoms, and maybe how you clean up the undercut rims. They'd be far more stable than conventional scrapers. Great idea if you want a really fine result.

 

[Lyle Jamieson]

I was turning last night, and something odd happened with one of my scrapers. This scraper is M2 HSS, and has been in use for quite some time with no problems raising a ground bur. This particular scraper failed to raise a ground bur as it usually did. My grinding wheel is Norton 8" SG 80gt. When I raise a ground bur, I usually run my finger to test it, and there was none detectable this time. This scraper performed poorly with this non existent bur. I tried raising a manually raised bur on this scraper, and no problems there....the manually raised bur appears and functions as normal......but, there is no detectable bur coming off the grinding wheel.

I tested using a few other scrapers, and the ground bur is the same as usual.....easily detectable with the finger on these other scrapers.

I used a diamond dresser and tested again......no change.

The platform angle was unchanged.

Anyone have any idea what the problem with this one scraper might be?

Anyone ever experience this?

Have I reached a spot where the M2 specs might be different? (Several inches of this scraper have been used up, and it previously produced a ground bur successfully.....but, not this time.)

-----odie-----

Hey Odie,
Most tool makers only heat treat the business end of the tool....the shanks is the holding area and never receives the hardening.
Thompson tools, are heat treated from end to end.
That's one reason why I have Doug Thompson make all my tools...

Regards,
Lyle

 

[Lars Hansen]

A few years ago, a friend and I studied two Sorby gouges closely as he noticed that there seemed to be a tiny bit of color change around 2¾" up from the tip.
We made the file test and the conclusion was precisely what Lyle writes: It seems that only the front 3" of the tools were hardened - induction hardened by sticking the front of the tool into a spool, I guess.
We jumped straight to similar Crown gouges and the same test suggested that they were hardened the full length af the flute plus ½".
Of course a *real* pro test would be nice, but I was pretty chocked, stopped using Sorby tools and sold what I had...

 

[Odie]

Hey Odie,
Most tool makers only heat treat the business end of the tool....the shanks is the holding area and never receives the hardening.
Thompson tools, are heat treated from end to end.
That's one reason why I have Doug Thompson make all my tools...

Regards,
Lyle

Hello Lyle......

The scraper in question is actually made from a metal cutting M2 lathe bit that is heat treated from end to end.....except this one, which is obviously not heat treated for the full length. Since there is no difference from one end to the other, it's quite common to grind both ends for metal lathe cutting purposes. See post #25

I do have a question about tools that are not hardened end to end. If the hardening is done only up to the end of the flute, why should it matter if the handle end is not heat treated?

A few years ago, a friend and I studied two Sorby gouges closely as he noticed that there seemed to be a tiny bit of color change around 2¾" up from the tip.
We made the file test and the conclusion was precisely what Lyle writes: It seems that only the front 3" of the tools were hardened - induction hardened by sticking the front of the tool into a spool, I guess.
We jumped straight to similar Crown gouges and the same test suggested that they were hardened the full length af the flute plus ½".
Of course a *real* pro test would be nice, but I was pretty chocked, stopped using Sorby tools and sold what I had...

Howdy Lars.....

I have completely worn out a number of gouges up to where the flute grind begins curving up.....some of them were Sorby. I have never experienced a loss of heat treating for the full length of the flute. Is it possible that this Sorby gouge you tested was not an example of standard heat treating Sorby uses for their gouges? An exception to the rule, I suspect.

Good day to both of you gentlemen.....

-----odie-----

Yes, thanks, Bill. My oven gets hotter than I've ever needed to use, but probably not 2200.

Odie, learning that you are using those short steel blanks for your scrapers led to an "Aha!" moment. Those must be what you use to get the round groove on your bowl bottoms, and maybe how you clean up the undercut rims. They'd be far more stable than conventional scrapers. Great idea if you want a really fine result.

Dean.....These special homemade scrapers are mostly for roughing bowls, and shear scraping. The shear scraping is done while being held in my homemade pvc handles, and the roughing is done while held in my repurposed wooden handles. Yes, they do have a purpose for the undercut rims, but most of that work is done with bowl gouges using a long traditional bevel grind. The round groove on my bowl bottoms is done with a bowl gouge, but has a traditional grind....not swept back. It's done very much like you would handle the gouge during spindle turning, but the orientation is side grain.

The real trick for negotiating these highly specialized cuts.....is to fully understand what I call "spiritual turning"......run a search on these forums for that.....

-----odie-----

 

[Gary Beasley]

The main reason for not heat treating the full length would be the chance of brittleness causing the tool to snap at the handle. The untreated metal being more prone to bend under extreme stress rather than crack.

 

[Lars Hansen]

@ Odie (#32):

They were both bowl gouges and both with the type of handle that ends in a fish tail with at metal button. Both were newish around 2015-16, one bought in the UK, one in Denmark.
Couldn't tell if they were freak samples, but I can't really imagine a production process that would allow certain gouges to be only partly hardened.

 

[Lyle Jamieson]

Hello Lyle......

The scraper in question is actually made from a metal cutting M2 lathe bit that is heat treated from end to end.....except this one, which is obviously not heat treated for the full length. Since there is no difference from one end to the other, it's quite common to grind both ends for metal lathe cutting purposes. See post #25

I do have a question about tools that are not hardened end to end. If the hardening is done only up to the end of the flute, why should it matter if the handle end is not heat treated?



Howdy Lars.....

I have completely worn out a number of gouges up to where the flute grind begins curving up.....some of them were Sorby. I have never experienced a loss of heat treating for the full length of the flute. Is it possible that this Sorby gouge you tested was not an example of standard heat treating Sorby uses for their gouges? An exception to the rule, I suspect.

Good day to both of you gentlemen.....

-----odie-----



Dean.....These special homemade scrapers are mostly for roughing bowls, and shear scraping. The shear scraping is done while being held in my homemade pvc handles, and the roughing is done while held in my repurposed wooden handles. Yes, they do have a purpose for the undercut rims, but most of that work is done with bowl gouges using a long traditional bevel grind. The round groove on my bowl bottoms is done with a bowl gouge, but has a traditional grind....not swept back. It's done very much like you would handle the gouge during spindle turning, but the orientation is side grain.

The real trick for negotiating these highly specialized cuts.....is to fully understand what I call "spiritual turning"......run a search on these forums for that.....

-----odie-----

Hi Odie,
For bowl gouges, some people like to use them all the down until the flute runs out. There is someplace along the line where the hardness is going to fade.

Hello Lyle......

The scraper in question is actually made from a metal cutting M2 lathe bit that is heat treated from end to end.....except this one, which is obviously not heat treated for the full length. Since there is no difference from one end to the other, it's quite common to grind both ends for metal lathe cutting purposes. See post #25

I do have a question about tools that are not hardened end to end. If the hardening is done only up to the end of the flute, why should it matter if the handle end is not heat treated?



Howdy Lars.....

I have completely worn out a number of gouges up to where the flute grind begins curving up.....some of them were Sorby. I have never experienced a loss of heat treating for the full length of the flute. Is it possible that this Sorby gouge you tested was not an example of standard heat treating Sorby uses for their gouges? An exception to the rule, I suspect.

Good day to both of you gentlemen.....

-----odie-----



Dean.....These special homemade scrapers are mostly for roughing bowls, and shear scraping. The shear scraping is done while being held in my homemade pvc handles, and the roughing is done while held in my repurposed wooden handles. Yes, they do have a purpose for the undercut rims, but most of that work is done with bowl gouges using a long traditional bevel grind. The round groove on my bowl bottoms is done with a bowl gouge, but has a traditional grind....not swept back. It's done very much like you would handle the gouge during spindle turning, but the orientation is side grain.

The real trick for negotiating these highly specialized cuts.....is to fully understand what I call "spiritual turning"......run a search on these forums for that.....

-----odie-----

 

[Odie]

Hi Odie,
For bowl gouges, some people like to use them all the down until the flute runs out. There is someplace along the line where the hardness is going to fade.

OK, thanks for the reply, Lyle.......

I usually continue to use my gouges for a little ways past the point where the flute begins to curve up, but I don't use them all the way to where the flute runs out. This is a matter of choice on my part, because the radial fulcrum lengthens with the change in the flute. I suppose it's possible that the heat treating might fade as some point.....however, by my methods of not completely using the tool up the end of the flute, I have not yet experienced running out of heat treated metal.

Thompson tools, are heat treated from end to end.
That's one reason why I have Doug Thompson make all my tools...

If your tools are heat treated from end to end, then why is that important to you?

-----odie-----